The Influence of Pt Surface Area on the Photo‐Enhancement of the Methanol Oxidation Reaction

The methanol oxidation reaction (MOR) on both Pt/TiO2/C and Pt/C‐based electrodes can be photo‐enhanced by illuminating the electrodes with UV light. This fact has called into question the role of TiO2 in the photo‐enhancement of MOR when Pt is present. To examine this further, we have studied the change in the photo‐enhancement of methanol electro‐oxidation with Pt surface area. For each catalyst, there was greater MOR activity in the presence of UV‐irradiation. However, upon potential cycling, there was a faster decline in MOR activity in the presence of UV‐irradiation compared to the MOR activity in the dark. A linear relation between the decay in methanol oxidation current with the decay in Pt surface area for both catalysts was observed. This strongly suggests that irradiation enhances the methanol oxidation process on the Pt surface. When TiO2 is present, it has a synergetic electronic effect that further enhances the oxidation process on the Pt surface. Does Pt surface area matter? The electro‐oxidation of methanol by on Pt/TiO2 catalysts can be photo‐enhanced by irradiation with UV‐visible light. The role of TiO2 in photo‐enhancement is a matter of some debate in the literature. Our experiments demonstrate that the photo‐enhanced methanol oxidation activity decays linearly with Pt surface area in the presence and absence of TiO2, which strongly suggests that there is an enhancement of electron‐transfer kinetics on the Pt surface.